Database table conversion

ABSTRACT

Methods, systems, and computer program products for converting a database table and implementing upgrades and/or migrations are described. A bridge schema comprising a bridge view for a table in a database of an original schema is created and a bridge application server instance is created, the bridge application server instance configured to utilize the bridge schema to access the table of the original schema. The table of the original schema is revised to conform to a specified target schema and a target application server instance configured to access the revised table is created.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior application Ser. No.14/920,362, filed on Oct. 22, 2015, which is incorporated by referenceherein in its entirety.

FIELD

The present disclosure relates generally to database tables. In anexample embodiment, the disclosure relates to a mechanism for revisingdatabase tables.

BACKGROUND

Database tables are widely used in the operations of applications, suchas business applications. The database tables often need to be revisedto accommodate different data types in their fields and/or to add newfields. For example, currency fields may need to be lengthened toaccommodate inflation. Material and order number fields may need to belengthened to accommodate transaction counts that evolve from thousandsto millions.

In some cases, it may prove difficult to extend the length of a fieldtype. For example, the character data type “NUMC” is only filled withnumbers; the numbers are right aligned and the field is filled with “0”characters from the left side. In some instances, it may be necessary tocopy the complete table to a new version of the table in order toincorporate a longer field for the cited data type, and to transfer thedata using an application level program. In the case of the “NUMC” datatype, the program reads the old value, creates a new value which isfilled with “0” characters from the left side, and the old value isappended to make the new number right aligned again and filled with theappropriate number of “0” characters from the left side. Thus, extendingdata types may lead to a “conversion” procedure which creates a newtable, copies the data to the new table, and replaces the old table withthe new table. The copying of the table may require additional memory(potentially equal to or greater than the size of the table) and mayresult in prevention of access to the table (i.e., downtime) since writeaccess during the revision process may not be possible.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1A illustrates a schematic diagram of an example system comprisingnetworked services and a landscape directory, in accordance with anexample embodiment;

FIG. 1B is a block diagram of a production system that is undergoing asoftware upgrade, in accordance with an example embodiment;

FIGS. 2A-2F show the fields of a table undergoing a conversion process,in accordance with an example embodiment;

FIG. 3A is a logical diagram of a production system and an originalschema prior to a software upgrade process, in accordance with anexample embodiment;

FIG. 3B illustrates the logical diagram of FIG. 3A with theincorporation of a bridge schema, in accordance with an exampleembodiment;

FIG. 3C illustrates the logical diagram of FIG. 3B with theincorporation of bridge application server instances, in accordance withan example embodiment;

FIG. 3D illustrates the logical diagram of FIG. 3C with the renaming ofthe repository, in accordance with an example embodiment;

FIG. 3E illustrates the logical diagram of FIG. 3D with theincorporation of the tables of the target schema, in accordance with anexample embodiment;

FIG. 3F illustrates the logical diagram of FIG. 3E after theincorporation of the version 2 application server instances of theproduction system, in accordance with an example embodiment;

FIG. 3G illustrates the logical diagram of FIG. 3F after the softwareupgrade of the production system, in accordance with an exampleembodiment.

FIGS. 4A-4C illustrate the logical diagram of a production system duringa rollback procedure, in accordance with an example embodiment;

FIG. 5 is a flowchart of an example method for upgrading software thatutilizes a database table, in accordance with an example embodiment;

FIG. 6 is a flowchart of an example method for converting a non-keyfield of a table, in accordance with an example embodiment;

FIG. 7 is a flowchart of a first example method for converting a keyfield of a table, in accordance with an example embodiment;

FIG. 8 is a flowchart of a second example method for converting a keyfield of a table, in accordance with an example embodiment;

FIG. 9 is a block diagram of an example database system for revisingtables and performing a software upgrade and/or migration, in accordancean example embodiment;

FIG. 10 is a block diagram illustrating mobile device, according to anexample embodiment; and

FIG. 11 is a block diagram of a computer processing system within whicha set of instructions, for causing the computer to perform any one ormore of the methodologies discussed herein, may be executed.

DETAILED DESCRIPTION

The description that follows includes illustrative systems, methods,techniques, instruction sequences, and computing program products thatembody example embodiments of the present invention. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide an understanding of various embodiments ofthe inventive subject matter. It will be evident, however, to thoseskilled in the art, that embodiments of the inventive subject matter maybe practiced without these specific details. In general, well-knowninstruction instances, protocols, structures and techniques have notbeen shown in detail.

Generally, methods, systems, apparatus, and computer program productsfor a conversion mechanism that converts (i.e., revises) a databasetable and a migration mechanism that is utilized to implement softwaresystem upgrades and/or migrations are described. In one exampleembodiment, a new table is created with a new structure thatincorporates a defined change(s) to an existing table. The definedchange may be the addition of a new field, or a change to an existingfield, such as a change of data type, a change to the length of thefield, and the like.

In one example embodiment, the data is read from the existing table, andstored in a new table that comprises the new field(s) and/or revisedfield(s). The old table is then removed and the name of the new table ischanged to match the name of the previously existing table. In oneexample embodiment, a table may be modified without creating a duplicatetable. One or more new fields are appended to the existing table, whereeach new field corresponds to an existing field that needs to beconverted or an additional field that needs to be added. Each new fieldhas a new name and has a structure that corresponds to the desiredstructure of the converted or additional field. After the new field iscreated, the new field is populated with the appropriate data. Forfields undergoing conversion, the previously existing field is deletedand the name of the new field is changed to match the name of thepreviously existing field.

FIG. 1A illustrates a schematic diagram of an example system 100comprising a database system 104, a production system 108, networkedservices 110, 112 and a landscape directory 120, in accordance with anexample embodiment. The production system 108 hosts variousapplications, such as business applications. The applications mayinclude multiple service applications (also referred to as “networkedservices”), such as networked services 110, 112 that may be distributedover a network and may be accessed by customers to process customers'requests and tasks. The networked services 110, 112 may be hosted bymultiple distributed servers that are interconnected via a network (suchas the public Internet, private networks, virtual private networks, andthe like). The networked services 110, 112 may be on-demand applications(e.g., applications that levy a charge based on use of the applicationsby customers), or conventional distributed applications for whichcustomers may have licenses. In one example embodiment, at least one ofthe service applications (e.g., service application 112) may be acloud-based application configured for cloud processing and may beavailable for use by multiple customers. In one example embodiment, atleast one application (e.g., networked service 110) may be an on-premiseapplication executing, for example, on a private network (which may bepart of the cloud or separate from the cloud). Although two networkedservices 110, 112 are depicted in FIG. 1A, any number of serviceapplications may be used.

As further depicted in FIG. 1A, the system 100 may include a landscapeview 150. The landscape view 150 may be an instance/component ofmonitoring tools, such as a monitoring tool 130, and may provide aholistic overview of a customer system landscape(s) involved in a cloudsolution(s). The landscape view 150 may enable viewing the datamaintained in the landscape directory 120. Additional applicationservices may be invoked to get more detailed information about thesystem landscape(s).

The landscape directory 120 may enable automatic connection ofpre-defined and pre-developed components (e.g., components that includeother applications and tools) of systems, including customer-specificsystems, on-demand systems, and the like. Such system managementfunctionality may be enabled, at least in part, through use of a bundleof interfaces to provide customers access to the customers' shared andprivate landscape data in the landscape directory 120. Thus, in oneexample embodiment, the landscape directory 120 may be configured tomaintain individual landscape data for various customers, where eachlandscape defines a customer's individual system, e.g., the identity ofa set of applications. For example, landscape data for one customer maydefine that customer's landscape as including networked services 110,112, while another customer's landscape data may define that customer'ssystem as including only service application 112. In one exampleembodiment, the landscape directory 120 may be implemented on one ormore storage devices (which may be distributed), and may be managed orcontrolled by a commercial or customized data management application.The landscape directory 120 may be on premise (and thus may be run froma customer's on-premise system or sub-system) or may be run from anon-demand platform using an application (e.g., a directory softwareapplication) as a service in hosted mode.

Landscape data in the landscape directory 120 may also include data thatdefines the connectivity between various applications, and may defineseparate connectivity configurations for the various customers that usethe identified applications. For example, the landscape data may setwhich services may communicate with each other (e.g., to transfer data,requests, commands, and the like), whether service applications mayautomatically initiate peer-to-peer communications with other serviceapplications without seeking a customer's input, and the like.

Landscape data maintained in the landscape directory 120 may furthercomprise registration information for the various service applications110, 112, including basic information pertaining to the serviceapplications 110, 112, such as the location of service applications 110,112 (provided, for example, as a uniform resource locator (URL) and thelike), the release version of the service applications 110, 112, theapplications' role(s) (e.g., human capital management applications,customer relationship management applications, and the like), usage type(e.g., whether the application is used for testing or in the course ofproduction), price/charge information, and the like. In one exampleembodiment, registration information for a service application 110 or112 maintained in the landscape directory 120 may be provided via aninterface (e.g., a registration interface 122). The registrationinformation may be provided by the services and/or may be provided,under some circumstances, by the customer(s) (e.g., in situations inwhich the system to be registered is a test system). In one exampleembodiment, the registration information may be included in each of theindividual landscapes for the various multiple customers where therespective service applications 110, 112 are listed, and/or may bemaintained in the landscape directory 120 as a global data record(providing information for the respective applications).

The landscape directory 120 may also be accessed through a discoveryinterface 124 that enables customers to retrieve information, such asthe registration information. Information retrieved via the discoveryinterface 124 may thus be used by customers to subscribe to additionalservice applications 110, 112 with respect to service applications 110,112 whose registration information was retrieved via the discoveryinterface 124, and to modify and/or edit a customers' landscape data(e.g., add or delete particular service applications 110, 112, changelandscape configurations, and the like).

The landscape directory 120 may also maintain access data pertaining tothe accessibility of the service applications 110, 112. The access datamay be communicated to the landscape directory 120 via, for example, astatus interface 126 and/or the registration interface 122. Access datamay include, for example, status and availability information for thevarious service applications 110, 112. Access data may be received fromadministrators (e.g., an administrator of the cloud, of private networksconnected to the cloud, of the service applications 110, 112 availableon the cloud, and the like), from the service applications 110, 112themselves, and/or from customers. Examples of access data may includestatus/availability information, information as to whether serviceapplications 110, 112 are active, information as to whether downtime isscheduled for any service application 110, 112, lifecycle statusinformation, and other such information. Lifecycle status informationmay include an indication of whether the service application 110, 112has been released, is obsolete, has been replaced by another serviceapplication 110, 112, and the like.

As shown in FIG. 1A, landscape data, including registration data, accessdata, and the like, may be arranged in data records that are stored inthe customers' (or tenants') individual landscape(s) in the landscapedirectory 120. For example, the landscape directory 120 may include anexample landscape 128 which may include multiple records defining theassociated customer's system (any number of records may be included in agiven landscape 128). The example landscape 128 may be stored in alogical area in memory allocated to store data for that landscape 128.

For example, FIG. 1A shows three records 140-1 through 140-3 includedwithin the landscape 128 that hold information, such as registrationinformation, for the service applications 110, 112 depicted in FIG. 1A.The record 140-1 may include information such as the identity of theservice application 110, namely service 1 (i.e., ser1, the abbreviationfor the networked service 110), an indication that the networked service110, 112 may include region or country-specific data, and informationabout the location of the networked service 110, 112 (e.g., its URL). Inthis case, the service application 110 may include data from anywhere inthe globe. Any of the records 140-1 through 140-3 may include additionaldata, including status/availability information, other types ofregistration information, and the like. Additional information that maybe included in at least some of the records 140-1 through 140-3 may bethe business usage of the system (e.g., customer relationship management(CRM), or human capital management (HCM) systems).

In one example embodiment, a collection of several callable services maybe bundled together to define a solution for which there may be a recordin a landscape. Defining a bundle of services in the landscape directory120 as a solution may enable monitoring customers' systems at a“solution-level” and not just at a “service level.”

The database system 104 is an organized collection of data. The datastored in the database system 104 includes tables, schemas, views,queries, and the like. A database management system (DBMS) is acomponent of the database system 104 and is an application that providesfor the capture, maintenance, querying, and analysis of data stored inthe database system 104. The DBMS is based on a database model, such asa relational model.

FIG. 1B is a block diagram of the production system 108 that isundergoing a software upgrade, in accordance with an example embodiment.As noted above, the production system 108 hosts various applications,such as the networked service 110.

The network 115 provides connectivity between, for example, theproduction system 108 and the database system 104. The network 115 maybe a local area network (LAN), a wireless network, a metropolitan areanetwork (MAN), a wide area network (WAN), a wireless network, a networkof interconnected networks, the public switched telephone network(PSTN), and the like.

During the software upgrade or migration, one or more tables in thedatabase system 104 may be added or revised. One or more bridgeapplication server instances 146-1, 146-2 may be instantiated and theoriginal application server instances 144-1, 144-2 of the productionsystem 108 may be temporarily relieved of their role in accessing thedatabase system 104 while the tables are added or revised. The bridgeapplication server instances 146-1, 146-2 allow applications of theproduction system 108 (that require access to tables that are undergoingconversion) to continue execution while the tables are added or revised,as described more fully below in conjunction with FIGS. 3A-3I.

An enqueue server (ENQ) 154 provides a service that is used by theapplication server's work processes to obtain an exclusive lock onobjects and records in a corresponding table(s). A process can request alock on an object and other processes are then prevented from changingthe locked object. This service is a singleton in the production system108 and is shared between the application server instances that have thedatabase connect to the original schema and the instances that have thedatabase connect to a bridge schema. A message server (MSG) 136 providesa service to exchange messages between application server instances,e.g. to start an asynchronous task in another process and forinter-process communication. The message server 136 is a singleton inthe production system 108 and is shared between the instances withoriginal and bridge database connect.

FIGS. 2A-2F show the fields of a table 200 undergoing a conversionprocess, in accordance with an example embodiment. As illustrated inFIG. 2A, the table 200 comprises a key field 204, a first field 208, anda second field 212-1. The second field 212-1 has a length of six digits.FIG. 2B shows the fields of a target table. The fields of the targettable are the same as the table 200, except that the second field 212-1has a length of ten digits and a third field 216 has been added. In oneexample embodiment, to create the target table of FIG. 2B, two fieldsare appended to the table 200 of FIG. 2A, as illustrated in FIG. 2C. Newfield 212-2 is to be the converted field of field 212-1 and has a lengthof ten digits; field 216 is the added field of the target table. Thefield 212-2 is temporarily named, for example, F2˜ and field 216 isnamed, for example, F3.

A trigger is created and used to copy the existing data of field 212-1to the new field 212-2, as illustrated in FIG. 21). Once the copying ofthe data is complete, the field 212-1 is dropped from the table, asillustrated in FIG. 2E. The newly converted field 212-2 (of ten digitsin length) may then be renamed to the name of the original field 212-1(i.e., F2), as illustrated in FIG. 2F. The conversion of the table isthen complete.

FIG. 3A is a logical diagram 300 of a production system 304 and anoriginal schema 312 prior to a software upgrade process, in accordancewith an example embodiment. The original schema 312 includes arepository table 314 and two application tables: table Appl1 316 andtable Appl2 318. The repository table 314 contains, for example, classfiles, object code, reports, dictionary definitions, configurationinformation, and the like. As described above, the production system 304comprises application server instances 310-1, 310-2 that access thetables Appl1 316 and Appl2 318, respectively. As signified by the v1legend, the repository table 314, the table Appl1 316, the table Appl2318, and the application server instances 310-1, 310-2 correspond to afirst version of the original schema 312.

The time chart in FIGS. 3A through 3G show the corresponding point inthe software upgrade process. As indicated in the time chart of FIG. 3A,the applications of the production system 108 initially use the version1 tables and views of the original (ORG) schema 312. A maintenance modeis entered where the applications of the production system 108 continueto use the version 1 tables and views of the original schema 312. Atransition is then made to the version 1 tables and views of a bridgeschema and business operations of the applications are restricted. Oncethe tables are revised, a transition is made to the version 2 tables andviews of a target schema.

FIG. 3B illustrates the logical diagram 300 with the incorporation of abridge schema 328, in accordance with an example embodiment. The bridgeschema 328 comprises a view for each table of the original schema 312.For example, the bridge schema 328 comprises a view Repo 330, a viewAppl1 332, and a view Appl2 334. The views of the bridge schema 328access the tables of the original schema 312 via optional aliases withinthe original schema 312. The aliases include Repo˜˜ 322 for accessingthe repository table 314, Appl1˜˜ 324 for accessing the table Appl1 316,and Appl2˜˜ 326 for accessing table Appl2 318. As configured in FIG. 3B,the bridge schema 328 provides access to the tables of the originalschema 312 while the tables of the original schema 312 undergoconversion. In addition, a new repository table Repo˜ 320 thatcorresponds to a target schema is created.

FIG. 3C illustrates the logical diagram 300 with the incorporation ofbridge application server instances 340-1, 340-2 in the productionsystem 304, in accordance with an example embodiment. The bridgeapplication server instances 340-1, 340-2 are configured to utilize thebridge schema 328 to access the tables of the original schema 312. Atransaction manager configures the applications of the production system304 to utilize the bridge application server instances 340-1, 340-2after a database transaction completes in order to ensure a smoothtransition from the application server instances 310-1, 310-2 to thebridge application server instances 340-1, 340-2. Once the transition ismade to the bridge application server instances 340-1, 340-2, the aliasRepo˜˜ 322 may be dropped and the original repository table 314 may berenamed Repo˜˜, thereby maintaining access to view Repo 330 and thecorresponding repository table 314, as illustrated in FIG. 3D.

FIG. 3E illustrates the logical diagram 300 with the incorporation ofthe tables of the target schema 350, in accordance with an exampleembodiment. In one example embodiment, the repository table Repo˜ 320that corresponds to the target schema 350 is renamed to the name of theoriginal repository table 314 (i.e., Repository) that corresponds to theoriginal schema 312. The two application tables of the original schema312, table Appl1 316 and table Appl2 318, are revised to conform to thetarget schema 350 (as denoted by the V2 legend). For example, therevised table Appl1 316 may have additional fields in comparison to theoriginal table Appl1 316. Similarly, the revised table Appl2 318 mayhave, for example, converted fields in comparison to the original tableAppl2 318.

A trigger 342 is created to copy the data from an existing field of thetable Appl2 318 to a new field, as illustrated in FIG. 3E. In oneexample embodiment, the trigger 342 transfers the data as it is changedby the application server instances 310-1, 310-2; a batch processtransfers the data which has not been changed by the application serverinstances 310-1, 310-2 since the addition of the corresponding new fieldto the table. In addition, the newly converted fields can be renamed, asdescribed above, and new indexes can be generated, if needed.

FIG. 3F illustrates the logical diagram 300 after the incorporation ofthe version 2 application server instances 344-1, 344-2 of theproduction system 304 in accordance with an example embodiment. Theversion 2 application server instances 344-1, 344-2 access the tables ofthe target schema 350, as illustrated in FIG. 3F, and thereby allow theversion 2 applications of the production system 304 to utilize theconverted tables. Once the applications of the production system 304transition to using the version 2 application server instances 344-1,344-2, the bridge schema 328, the aliases Appl1˜˜ 324 and Appl2˜˜ 326,and the repository table Repo˜˜ 322 may be dropped. FIG. 3G illustratesthe logical diagram 300 after the software upgrade of the productionsystem 304, in accordance with an example embodiment.

In some instances, a failure may occur during the software upgrade ormigration process. For example, duplicate field names or failure to getan exclusive lock on a table may result in a failure of the upgradeprocess. In this case, it may be necessary to roll-back the tableconversion process. FIGS. 4A-4D illustrate the logical diagram 300 ofthe production system 304 during a rollback procedure, in accordancewith an example embodiment. FIG. 4A illustrates an example state of theproduction system 304 when a failure may occur, in accordance with anexample embodiment. In the example of FIG. 4A, the trigger 342 has beencreated and the copying of the data is underway. In case of failure, thetrigger 342 can be dropped and the new fields that were added to thetables (i.e., table Appl1 316 and table Appl2 318) are removed, asillustrated in FIG. 4B. The bridge schema 328, the aliases Appl1˜˜ 324and Appl2˜˜ 326, and the repository table 314 may be dropped (and bereplaced by the version 1 repository table 314 of the original schema312). FIG. 4C illustrates the logical diagram 300 after the roll-back ofthe software upgrade or migration of the production system 304, inaccordance with an example embodiment.

FIG. 5 is a flowchart of an example method 500 for upgrading softwarethat utilizes a database table, in accordance with an exampleembodiment. In one example embodiment, one or more of the operations ofthe method 500 are performed by the table conversion module 906.

In one example embodiment, the bridge schema 328 is created (operation504). As illustrated in FIG. 3B, the bridge schema 328 comprises a viewfor each table of the original schema. For example, the bridge schema328 comprises a view Repo 330, a view Appl1 332, and a view Appl2 334.Aliases are created within the original schema 312 for the table(s) ofthe original schema 312 (operation 508). As noted above, the views ofthe bridge schema 328 access the tables of the original schema 312 viathe aliases within the original schema 312. The aliases include Repo˜˜322 for accessing the repository table 314, Appl1˜˜ 324 for accessingthe table Appl1 316, and Appl2˜˜ for accessing table Appl2 318. Inaddition, a new repository table Repo˜ 320 that corresponds to thetarget schema 350 is created (operation 512). The alias Repo˜˜ 322 maybe dropped and the repository table 314 of the original schema 312 isrenamed with the name of the dropped alias (i.e., Repo˜˜) (operation516), as illustrated in FIG. 3D.

The bridge application server instances 340-1, 340-2 are created withinthe production system 304 and are configured to utilize the bridgeschema 328 in order to access the tables of the original schema 312(operation 520). As noted above, a transaction manager moves theapplications to utilize the bridge application server instances 340-1,340-2 after a database transaction completes in order to ensure a smoothtransition between the different application servers.

The repository table 320 that corresponds to the target schema 350 isrenamed with the original name of the repository table 314 of theoriginal schema 312, as illustrated in FIG. 3E (operation 524).

The tables of the original schema 312 (e.g., table Appl1 316 and tableAppl2 318) are revised to conform to the target schema 350 (operation528). For example, a trigger 342 may be created to copy the data in anexisting field to a new field, as illustrated in FIG. 3E. In addition,the newly converted fields can be renamed, as described above, and newindexes may be generated, if needed. The version 2 application serverinstances 344-1, 344-2 are created and a rollover to the tables of thetarget schema 350 is performed (operation 532). The version 2application server instances 344-1, 344-2 are configured to access thetables of the target schema 350, as illustrated in FIG. 3F. The bridgeschema 328, the aliases (e.g., aliases Appl1˜˜ 324 and Appl2˜˜ 326), andthe repository table (Repo˜˜ 322) are dropped (operation 536). Thetransition to the target schema 350 is complete, as illustrated in FIG.3G.

FIG. 6 is a flowchart of an example method 600 for converting a non-keyfield of a table, in accordance with an example embodiment. In oneexample embodiment, one or more of the operations of the method 600 areperformed by the table conversion module 906.

In one example embodiment, a structure of a new table, i.e. the table ofa target schema 350 to be converted to, is analyzed and non-key fieldsthat need to be converted are identified (operation 604). For example,an existing table may have fields K1, F1, and F2, where K1 is a keyfield and F2 is character data type “NUM” of six-digit length. If thenew table has identical fields to the existing table except for anadditional field F3 and for Field F2 having a length of ten digits, thenfield F2 would be identified as needing conversion to a length of tendigits and field F3 would be identified as needing to be added.

The existing table is renamed (for example, to Table_temp) and a viewTable is created with the name of the original table (e.g., Table1)where all fields of the table are selected in the list of fields(operation 608). For example, all fields of Table 1 are selected byexplicitly specifying the fields in the list of fields (e.g., createview Table as select K1, F1, F2 from Table_temp). The view is part ofthe table link of the database system 104. If supported, this step isperformed in one database transaction. If access to the table resultsin, for example, an SQL error indicating that the table does not exist,the access should be retried.

A new field is then appended to the temporarily named table (i.e.,Table_temp) for each field identified as being in need of conversion andfor each additional field, where the new field is of the type defined inthe new table (operation 612). The fields that are appended for thefields in need of conversion are given temporary names. For example, thenew field appended for field F2 is named F2_Tmp. New fields that areappended for additional fields are given their target name, such asfield F3.

A trigger 342 is created for each field in need of conversion in orderto update the corresponding new field (operation 616). In one exampleembodiment, the trigger 342 is created for the table and does theconversion of all fields. Depending on the type of database, differenttriggers may be used for insert and update statements. The trigger 342performs the content conversion, copying data from, for example, fieldF2 to field F2_Tmp and converting the data from data type NUMC 6 to datatype NUMC 10. In one example embodiment, a database procedure is calledto copy the data of the field F2 (that has not changed since thecreation of the corresponding new field) to the field F2_Tmp.

The consumption of the table, if enabled, is disabled (operation 620).The old field(s), such as F2, are dropped (by, for example, performingthe operation alter table drop column F2); the new converted field(s)are renamed, such as renaming field F2_Tmp as F2, (by, for example,performing the operation alter table rename column F2_Tmp to F2); theview Table is dropped; and the table Table_Tmp is renamed to theoriginal name of the table (by, for example, performing the operationrename table Table_Tmp to Table) (operation 624). Secondary indexes arerecreated using the converted fields, if necessary (operation 628). Theconversion of the table is complete and the consumption of the table isenabled (operation 632).

FIG. 7 is a flowchart of a first example method 700 for converting a keyfield of a table, in accordance with an example embodiment. In oneexample embodiment, one or more of the operations of the method 700 areperformed by the table conversion module 906.

In one example embodiment, a structure of a new table, i.e. the table tobe converted to, is analyzed and additional fields and/or fields whichneed to be converted are identified (operation 704). For example, anexisting table may have fields K1, K2, F1, and F2, where K1 and K2 arekey fields and K1 is of character data type “NUMC” and has a length ofsix characters. If the new table has identical fields to the existingtable except for an additional field F3 and for field F2 having a lengthof ten characters (instead of six characters), then field F2 would beidentified as needing conversion to a length of ten characters and fieldF3 would be identified as needing to be added.

The existing table is renamed to, for example, Table_Temp and a viewTable is created with the name of the original table (e.g., Table1)(operation 708). In one example embodiment, all fields of Table1 areselected by explicitly specifying fields of the temporarily named tablein the list of fields (e.g., create view Table as select K1, K2, F1, andF2). The created view is part of the table link of the database system104. In one example embodiment, operation 708 is performed in onetransaction. If access to the table results in, for example, an SQLerror indicating that the table does not exist, the access may beretried. In one example embodiment, the retry can be performed by thedatabase interface in the application server. In this way, the temporarylack of availability of the table is hidden from the consumer of theapplication.

A new field is then appended to the temporarily named table (Table_temp)for each field identified as being in need of conversion and for eachnew additional field, where the new field is of the type defined in thenew table (operation 712). The fields that are appended for the fieldsin need of conversion are given temporary names. For example, the newfield appended for key field K1 is named K1_Temp. New fields that are tobe appended for additional fields are given their target name, such asfield F3. Also, since K1 is a key field, the temporary field K1_Temp isappended as a “nullable” field and, as a non-key field, a standard datafield. The append done as “nullable” is a fast database operation; thisis necessary, as this type of database operation uses an exclusive lockon the table and the impact on the use of the table should be minimized.The field is later altered to exhibit the default behavior, as needed bythe application.

A trigger 342 is created for each field in need of conversion (operation716). The trigger 342 is used to update the new field (K1_Temp) that isbeing converted to. The trigger 342 performs the content conversion,copying data from field K1 to field K1_Temp, and, for example,converting the data from data type NUMC 6 to data type NUMC 10. In oneexample embodiment, the copying is performed by the database triggerwithin the same database transaction as updates to the row containingthe data for the original corresponding field and within the samedatabase transaction as inserts of new rows. In one example embodiment,a database procedure is called to copy the data from all entries of thefield K1 (that have not changed since the creation of the correspondingnew field) to the new field (K_Temp). The trigger 342 remains in place,thereby keeping the data consistent between field K1 and field K1_Temp(as updates to the data are performed and inserts of new rows areperformed). For a deletion of a row, the trigger does not need toperform any action, as the row including the new field(s) is deleted.

The temporary and new fields are appended as “nullable” to enable addingthe fields during use of the table with minimal impact for the users ofthe table. The fields have to be set to their desired default valuebefore the switch can be performed. The fields thus have to be set to“not null, default<some default, e.g. space>”. If the database type usedcan execute the alter table statement (e.g., alter table TAB altercolumn COL default DEFAULT_VAL NOT NULL) with minimum impact for theconsumer of the table, this operation can be done during uptime of thetable (i.e., while the table is accessible by, for example, anapplication). If the runtime of the statement depends on the databasesize, the table downtime starts before the statement is executed. If thetable is in use and the alter statement is fast, the new uniqueconstraint can be added (including the target column K1_TEMP). Again, ifthis statement can be executed with minimum impact for the consumer ofthe table, this step can be executed during the uptime of the table;otherwise, the step is executed while the table is in downtime.Depending on the capabilities of the database, the unique constraint onK1_TEMP and the other keys can be used as the new primary key constraint(once K1_TEMP is renamed to K1). This would enable running theoperations for key fields with minimum downtime as well.

In one example embodiment, if the table is already in downtime (i.e.,access to the table is disabled), a new unique key constraint (e.g.,Table_Uni_New) is created on K1_Temp and K2 (operation 720).

The consumption of the table is disabled (operation 724). The existingprimary key constraint (e.g., Table_Uni) on K1 and K2 is dropped; theoriginal field(s) in need of conversion, such as K1, are dropped (by,for example, performing the operation alter table drop column K1); theunique key constraint (i.e., Table_Uni_New) is dropped (assuming theunique key constraint exists and is invalidated upon renaming thecolumn); the new converted field(s) are renamed, such as renaming fieldK1_Temp as K1 (by, for example, performing the operation alter tablerename column K1_Temp to K1); the view Table is dropped; and the tableis renamed to the name of the original table (by, for example,performing the operation rename table Table_Temp to Table) (operation728). A new primary key constraint for K1 and K2 (e.g., Table_Uni) iscreated and secondary indexes are recreated, if necessary (operation732). The conversion of the table is complete and the consumption of thetable is enabled (operation 736).

FIG. 8 is a flowchart of a second example method 800 for converting akey field of a table, in accordance with an example embodiment. In oneexample embodiment, one or more of the operations of the method 800 areperformed by the table conversion module 906.

In one example embodiment, a structure of a new table, i.e. the table tobe converted to, is analyzed and additional fields and/or fields whichneed to be converted are identified (operation 804). For example, anexisting table may have fields K1, K2, F1, and F2, where K1 and K2 arekey fields and K1 is of character data type “NUMC” and has a length ofsix characters. If the new table has identical fields to the existingtable except for an additional field F3 and for field F2 having a lengthof ten characters (instead of six characters), then field F2 would beidentified as needing conversion to a length of ten characters and fieldF3 would be identified as needing to be added.

The existing table is renamed to, for example, Table_Temp and a viewTable is created with the name of the original table (e.g., Table1)(operation 808). In one example embodiment, all fields of Table1 areselected by explicitly specifying fields of the temporarily named tablein the list of fields (e.g., create view Table as select K1, K2, F1,F2). The created view is part of the table link of the database system104. In one example embodiment, operation 808 is performed in onetransaction. If access to the table results in, for example, an SQLerror indicating that the table does not exist, the access may beretried.

A new field is then appended to the temporarily named table (Table_temp)for each field identified as being in need of conversion and for eachnew additional field, where the new field is of the type defined in thenew table (operation 812). The fields that are appended for the fieldsin need of conversion are given temporary names. For example, the newfield appended for field K1 is named K1_Temp. New fields that areappended for additional fields are given their target name, such asfield F3. Also, since K1 is a key field, the temporary field K1_Temp isappended as a “nullable” field.

A trigger 342 is created for each field in need of conversion (operation816). The trigger 342 is used to update the new field (K1_Temp) that isbeing converted. The trigger 342 performs the content conversion,copying data from, for example, field K1 to field K1_Temp, andconverting the data from data type NUMC 6 to data type NUMC 10. In oneexample embodiment, the copying is performed within the same databasetransaction as updates to and inserts of the row containing the data forthe original corresponding field. In one example embodiment, a databaseprocedure is called to copy the data from all entries of the field K1that have not changed since the creation of the corresponding field tothe new field (K1_Temp). The trigger 342 remains in place, therebykeeping the data consistent between field K1 and field K1_Temp (asupdates to the data are performed).

The consumption of the table, if enabled, is disabled (operation 820).The new converted key field (e.g., column K1_Temp) is changed to “notnull” (by, for example, performing the operation alter column K1_Temp to“not null”). The existing primary key constraint (e.g., Table_Uni) on K1and K2 is dropped; the original converted field(s), such as K1, aredropped (by, for example, performing the operation alter table dropcolumn K1), the new field(s) are renamed, such as renaming field K1_Tempas K1 (by, for example, performing the operation alter table renamecolumn K1_Temp to K1); the view Table is dropped, and the table isrenamed to the name of the original table (by, for example, performingthe operation rename table Table_Temp to Table) (operation 824). A newprimary key constraint for K1 and K2 (e.g., Table_Uni) is created andsecondary indexes are recreated, if necessary (operation 828). Theconversion of the table is complete and the consumption of the table isenabled (operation 832).

FIG. 9 is a block diagram 900 of an example database system 104 forrevising tables and performing a software upgrade and/or migration, inaccordance an example embodiment. The database system 104 is shown toinclude a processing system 902 that may be implemented on a server,client, or other processing device that includes an operating system 904for executing software instructions. In accordance with an exampleembodiment, the database system 104 includes a table conversion module906, a database management module 910, a software upgrade managementmodule 914, and a user interface module 918.

The table conversion module 906 manages the conversion of a databasetable. The table conversion module 906 manages the conversion of fieldsof the table and the addition of new fields, as needed. The tableconversion module 906 instantiates triggers 342 to copy data betweenfields and handles the renaming of tables and fields. The tableconversion module 906 participates in a conversion rollback if a failureis encountered during the conversion process.

The database management module 910 provides for the capture,maintenance, querying, and analysis of data stored in the databasesystem 104. The database management module 910 is based on a databasemodel, such as a relational model. The software upgrade managementmodule 914 manages the creation of the bridge schema 328, the aliases322, 324, 326, and the repository tables 314, 320. The software upgrademanagement module 914 also manages the conversion rollback, if a failureis encountered during the conversion process. The user interface module918 enables a user, such as an administrator, developer, and the like,to initiate a software upgrade and/or migration and to monitor theupgrade or migration process, as described above.

FIG. 10 is a block diagram illustrating a mobile device 1000, accordingto an example embodiment. The mobile device 1000 can include a processor1002. The processor 1002 can be any of a variety of different types ofcommercially available processors suitable for mobile devices 1000 (forexample, an XScale architecture microprocessor, a Microprocessor withoutInterlocked Pipeline Stages (MIPS) architecture processor, or anothertype of processor). A memory 1004, such as a random access memory (RAM),a Flash memory, or other type of memory, is typically accessible to theprocessor 1002. The memory 1004 can be adapted to store an operatingsystem (OS) 1006, as well as applications 1008, such as a mobilelocation enabled application that can provide location-based services(LBSs) to a user. The processor 1002 can be coupled, either directly orvia appropriate intermediary hardware, to a display 1010 and to one ormore input/output (I/O) devices 1012, such as a keypad, a touch panelsensor, and a microphone. Similarly, in some embodiments, the processor1002 can be coupled to a transceiver 1014 that interfaces with anantenna 1016. The transceiver 1014 can be configured to both transmitand receive cellular network signals, wireless data signals, or othertypes of signals via the antenna 1016, depending on the nature of themobile device 1000. Further, in some configurations, a GPS receiver 1018can also make use of the antenna 1016 to receive GPS signals.

FIG. 11 is a block diagram of a computer processing system 1100 withinwhich a set of instructions 1124 may be executed for causing a computerto perform any one or more of the methodologies discussed herein. Insome embodiments, the computer operates as a standalone device or may beconnected (e.g., networked) to other computers. In a networkeddeployment, the computer may operate in the capacity of a server or aclient computer in server-client network environment, or as a peercomputer in a peer-to-peer (or distributed) network environment.

In addition to being sold or licensed via traditional channels,embodiments may also, for example, be deployed by software-as-a-service(SaaS), application service provider (ASP), or by utility computingproviders. The computer may be a server computer, a personal computer(PC), a tablet PC, a set-top box (STB), a personal digital assistant(PDA), a cellular telephone, or any processing device capable ofexecuting a set of instructions (sequential or otherwise) that specifyactions to be taken by that device. Further, while only a singlecomputer is illustrated, the term “computer” shall also be taken toinclude any collection of computers that, individually or jointly,execute a set multiple sets) of instructions to perform any one or moreof the methodologies discussed herein.

The example computer processing system 1100 includes a processor 1102(e.g., a central processing unit (CPU), a graphics processing unit(GPU), or both), a main memory 1104, and a static memory 1106, whichcommunicate with each other via a bus 1108. The computer processingsystem 1100 may further include a video display 1110 (e.g., a plasmadisplay, a liquid crystal display (LCD), or a cathode ray tube (CRT)).The computer processing system 1100 also includes an alphanumeric inputdevice 1112 (e.g., a keyboard), a user interface (UI) navigation device1114 (e.g., a mouse and/or touch screen), a drive unit 1116, a signalgeneration device 1118 (e.g., a speaker), and a network interface device1120.

The drive unit 1116 includes a machine-readable medium 1122 on which isstored one or more sets of instructions 1124 and data structuresembodying or utilized by any one or more of the methodologies orfunctions described herein. The instructions 1124 may also reside,completely or at least partially, within the main memory 1104, thestatic memory 1106, and/or within the processor 1102 during executionthereof by the computer processing system 1100, the main memory 1104,the static memory 1106, and the processor 1102 also constitutingtangible machine-readable media 1122.

The instructions 1124 may further be transmitted or received over anetwork 1126 via the network interface device 1120 utilizing any one ofa number of well-known transfer protocols (e.g., Hypertext TransferProtocol).

While the machine-readable medium 1122 is shown in an example embodimentto be a single medium, the term “machine-readable medium” should betaken to include a single medium or multiple media (e.g., a centralizedor distributed database, and/or associated caches and servers) thatstore the one or more sets of instructions 1124. The term“machine-readable medium” shall also be taken to include any medium thatis capable of storing, encoding, or carrying a set of instructions 1124for execution by the computer and that cause the computer to perform anyone or more of the methodologies of the present application, or that iscapable of storing, encoding, or carrying data structures utilized by orassociated with such a set of instructions 1124. The term“machine-readable medium” shall accordingly be taken to include, but notbe limited to, solid-state memories and optical and magnetic media.

EXAMPLES

Example 1 is a computerized method for performing an upgrade, the methodcomprising: creating a bridge schema comprising a bridge view in thebridge schema for a table in a database of an original schema; creatinga bridge application server instance, the bridge application serverinstance configured to utilize the bridge schema containing the bridgeview to access the table of the original schema; revising, using one ormore hardware processors, the table of the original schema to conform toa specified target schema; and creating a target application serverinstance configured to access the revised table.

In Example 2, the subject matter of Example 1 optionally includescreating an alias for the table of the original schema, the alias beingthe target of the corresponding view in the bridge schema, the viewbeing defined to select from the alias of the table.

In Example 3, the subject matter of Example 2 optionally includesdropping the alias for the table of the original schema.

In Example 4, the subject matter of Example 1 optionally includesconfiguring an application running in the application server instance toaccess the bridge schema and the views defined in the bridge schema.

In Example 5, the subject matter of Example 4 optionally includeswherein only fields of the table conforming to the original schema areaccessible to the application via the bridge application serverinstance.

In Example 6, the subject matter of Example 4 optionally includesconfiguring the application to execute in the target application serverinstance.

In Example 7, the subject matter of Example 6 optionally includeswherein fields of the table conforming to the specified target schemaare accessible to the application executing in the target applicationserver instance.

In Example 8, the subject matter of Example 1 optionally includescreating a target repository table that corresponds to the specifiedtarget schema.

In Example 9, the subject matter of Example 8 optionally includesdropping an alias for a source repository table of the original schema,the source repository table having a name, and renaming the sourcerepository table to the name of the dropped alias for the sourcerepository table.

In Example 10, the subject matter of Example 9 optionally includesrenaming the target repository table that corresponds to the targetschema to the name of the source repository table of the originalschema.

In Example 11, the subject matter of Example 1 optionally includesdropping the bridge schema.

Example 12 is an apparatus for performing an upgrade, the apparatuscomprising: one or more processors; memory to store instructions that,when executed by the one or more hardware processors perform operationscomprising: creating a bridge schema comprising a bridge view for atable in a database of an original schema; creating a bridge applicationserver instance, the bridge application server instance configured toutilize the bridge schema to access the table of the original schema;revising, using one or more hardware processors, the table of theoriginal schema to conform to a specified target schema; and creating atarget application server instance configured to access the revisedtable.

In Example 13, the subject matter of Example 12 optionally includesinstructions that, when executed by the processor cause the processor tocreate an alias for the table of the original schema.

In Example 14, the subject matter of Example 13 optionally includesinstructions that, when executed by the processor cause the processor todrop the alias for the table of the original schema.

In Example 15, the subject matter of Example 12 optionally includesinstructions that, when executed by the processor cause the processor toconfigure an application to access the bridge application serverinstance.

In Example 16, the subject matter of Example 15 optionally includeswherein only fields of the table conforming to the original schema areaccessible to the application via the bridge application serverinstance.

In Example 17, the subject matter of Example 15 optionally includesinstructions that, when executed by the processor cause the processor toconfigure the application to execute in the target application serverinstance.

In Example 18, the subject matter of Example 17 optionally includeswherein fields of the table conforming to the specified target schemaare accessible to the application executing in the target applicationserver instance.

In Example 19, the subject matter of any one or more of Examples 12-18optionally include instructions that, when executed by the processorcause the processor to create a target repository table that correspondsto the specified target schema, drop an alias for a source repositorytable of the original schema, the source repository table having a name,rename the source repository table to the name of the dropped alias forthe source repository table, rename the target repository table thatcorresponds to the target schema to the name of the source repositorytable of the original schema, and drop the bridge schema.

Example 20 is a computer-readable medium embodying instructions that,when executed by a processor, perform operations comprising: creating abridge schema comprising a bridge view for a table in a database of anoriginal schema; creating a bridge application server instance, thebridge application server instance configured to utilize the bridgeschema to access the table of the original schema; revising, using oneor more hardware processors, the table of the original schema to conformto a specified target schema; and creating a target application serverinstance configured to access the revised table.

While the embodiments of the invention(s) is (are) described withreference to various implementations and exploitations, it will beunderstood that these embodiments are illustrative and that the scope ofthe invention(s) is not limited to them. In general, techniques formaintaining consistency between data structures may be implemented withfacilities consistent with any hardware system or hardware systemsdefined herein. Many variations, modifications, additions, andimprovements are possible.

Plural instances may be provided for components, operations, orstructures described herein as a single instance. Finally, boundariesbetween various components, operations, and data stores are somewhatarbitrary, and particular operations are illustrated in the context ofspecific illustrative configurations. Other allocations of functionalityare envisioned and may fall within the scope of the invention(s). Ingeneral, structures and functionality presented as separate componentsin the exemplary configurations may be implemented as a combinedstructure or component. Similarly, structures and functionalitypresented as a single component may be implemented as separatecomponents. These and other variations, modifications, additions, andimprovements fall within the scope of the invention(s).

What is claimed is:
 1. A computerized method for converting a tablestored in a database, the method comprising: accessing a data structureto obtain an identification of one or more differences of a source tablein the database and a specified target table; appending, using one ormore hardware processors, a new field to the source table for a field ofthe source table in need of conversion, the appended new fieldcorresponding to a key field, wherein the field of the source table inneed of conversion has a name; changing the appended new field to notnull; deleting an existing primary key constraint; deleting, in thedatabase, the field of the source table in need of conversion; renaming,in the database, the new field corresponding to the field in need ofconversion to the name of the field of the source table in need ofconversion; and creating a new primary key constraint; creating aprocessor-driven trigger for the field of the source table in need ofconversion; and copying, using the one or more processors, data betweenthe field of the source table in need of conversion and thecorresponding new field using the processor-driven trigger.
 2. Themethod of claim 1, further comprising analyzing the source table and thespecified target table to identify the one or more differences.
 3. Themethod of claim 1, further comprising appending an additional field tothe source table for each additional field of the specified target tablein comparison to the source table.
 4. The method of claim 1, wherein aconversion of the field comprises one or more of a change of data typeand a change to a data length.
 5. The method of claim 1, furthercomprising: renaming the source table; and creating a view of the sourcetable using a previous name of the source table.
 6. The method of claim5, wherein all fields of the source table are selected in acorresponding list of fields.
 7. The method of claim 5, furthercomprising: dropping the view; and renaming the source table to theprevious name.
 8. The method of claim 5, wherein the creation of theview is performed in one database transaction.
 9. The method of claim 1,further comprising temporarily naming the new field during at least aportion of the conversion process.
 10. The method of claim 1, whereinthe processor-driven trigger copies data for a plurality of fields inneed of conversion.
 11. The method of claim 1, wherein theprocessor-driven trigger converts data from a first type to a secondtype.
 12. The method of claim 1, further comprising calling a databaseprocedure to copy data from the field of the source table in need ofconversion to the corresponding new field.
 13. The method of claim 1,further comprising creating a secondary index using the new field. 14.An apparatus for converting a table stored in a database, the apparatuscomprising: one or more hardware processors; memory to storeinstructions that, when executed by the one or more hardware processors,perform operations comprising: accessing a data structure to obtain anidentification of one or more differences of a source table in adatabase and a specified target table; appending a new field to thesource table for a field of the source table in need of conversion, theappended new field corresponding to a key field, wherein the field ofthe source table in need of conversion has a name; changing the appendednew field to not null; deleting an existing primary key constraint;deleting, in the database, the field of the source table in need ofconversion; renaming, in the database, the new field corresponding tothe field in need of conversion to the name of the field of the sourcetable in need of conversion; and creating a new primary key constraint;creating a processor-driven trigger for the field of the source table inneed of conversion; and copying data between the field of the sourcetable in need of conversion and the corresponding new field using theprocessor-driven trigger.
 15. The apparatus of claim 14, wherein theappended new field corresponds to a key field and is a nullable field.16. The apparatus of claim 15, further comprising creating a unique keyconstraint on the appended new field that corresponds to the key field.17. The apparatus of claim 16, further comprising: disabling consumptionof the table; deleting an existing primary key constraint; deleting, inthe database, the field of the source table in need of conversion;renaming, in the database, the new field corresponding to the field inneed of conversion to the name of the field of the source table in needof conversion; and creating a new primary key constraint.
 18. Acomputer-readable medium embodying instructions that, when executed by aprocessor, perform operations comprising: accessing a data structure toobtain an identification of one or more differences of a source table ina database and a specified target table; appending a new field to thesource table for a field of the source table in need of conversion, theappended new field corresponding to a key field, wherein the field ofthe source table in need of conversion has a name; changing the appendednew field to not null; deleting an existing primary key constraint;deleting, in the database, the field of the source table in need ofconversion; renaming, in the database, the new field corresponding tothe field in need of conversion to the name of the field of the sourcetable in need of conversion; and creating a new primary key constraint;creating a processor-driven trigger for the field of the source table inneed of conversion; and copying data between the field of the sourcetable in need of conversion and the corresponding new field using theprocessor-driven trigger.
 19. The medium of claim 18, the operationsfurther comprising appending an additional field to the source table foreach additional field of the specified target table in comparison to thesource table.
 20. The medium of claim 18, the operations furthercomprising: renaming the source table; and creating a view of the sourcetable using a previous name of the source table.